Gas distribution method and apparatus



Jan. 9, 1951 J, DETHEROW 2,537,815

GAS DISTRIBUTION METHOD AND APPARATUS Filed Feb 9, 1948 L/A 505 A 175THE/917W IN V EN TOR.

A TTORNE Y.

Patented Jan. 9, 1951 UNITED .s TATTEJS PATENT OFFICE GAS DISTRIBUTION.METIHOD AND APPARATUS 3 Claims.

This invention relates generally to gas distributing systems, and moreparticularly to a novel method of operating "such systems, and toequipment for facilitating the novel operation of such systems.

The "invention is capable of use with distributing 'or dispensingsystems which handle various types of vaporized gases, such as air,carbon dioxide, natural gas, etc, as well as with systems for storinggas in 'looth its liquid "and vapor phases and subsequentlydistributingthe gas in vaporized form, the latter systems including the liquefiedpetroleum gases such :asbutane, propane, and any combination ofbutane-propane.

The "vaporized gas handled by such systems normally carries a smallamount :oi "Water in vaporized form, and is'moved under relatively highpressure from -a'isource .of supply through :a cond-uit'to or near to apoint of use, adjacent which point "it is fed through :a pressurereducer, or :a series of such reducers, in order toxdeliver it to gasusing applances at the desired low pressure. During the reduction of"pressure in the pressure reducers, a rapid-expansion of the :gasoccurs. This :rapid expansion, in accordance with the laws of physics,produceszan extreme drop in thetemperature of :the .:gas. This flowtemperature causes condensation of the *water vapor contained in thegas, and prompt freezing of the condensate at :or near the :pressurereducer inlet. Such ice formation often-completely seals the inlet andconsequentlycuts 'ofi it-he flow {of gas to the gas :using appliances.This stoppage of flow not :only causes extreme inconvenience, but .mayoftentimes be very dangerous; The reason is that the "air or earthsurrounding the pressure reducer is often :at a temperature abovefreezing, resulting .in the gradual thawing of the ice which hasthrottled the gas flow. When the .ice has melted sufiiciently, gasa'gai-nbeginsa-to .fiow through-the reducer and to the .gas usingappliances. Unless the appliances were shut off during the gas flowstoppage, raw gas begins to escape :into the room or building in whichthe appliances are located. TIT-he gas accumulates and creates both .aneaplosionand fire hazard.

It is .the primary :obj ectlof this invention, .therehire, to provide .agas-distributing system, and a method of operating it, which preventsthe freezing of moisture-carried by the :gas when that moisture iscondensed to .a liquid and subjected to .a temperature Well below thefreezing temperature of Water.

It is another object ,of this invention to provide a methodof operatinggas distributing and dispensing systems which includes the step ofintroducing into the gas, prior to its rapid expansion and consequentcooling, a sufiic'ient quantity of-a suitable anti-freeze vapor toprevent the freezing of moisture which is condensed from the gas by lowoperating temperatures at ornea-r the'po'i-nt of expansion. I

"It is another objectto provide an improved gas distributing systemwhich includes a means of introducing anti-freeze vapor into the gasprior to its arrival at the pressure reducer, the quantity eranti-freeze vapor being sufiicient to prevent the freezing of moistureatthe pressure reducer inlet, or at any point in the service linebetweenthe point'of introduction of the antifreeze vapor and the pointof use of the gas.

"It "is'an additional object to provide a device for connection into thegas transmission or service line of any gas distributing systemcurrently in use or currently available, which will automaticallyintroduce into :thegas flowing through the pipe a sufficient quantity ofantifreeze vapor to -prevent the freezing of mosture contained in the 7gas when such :moisture is 1 condensed to a liquid by cooling, andsubjected to temperatures well below the freezingpoint :of water.

Both the :method and apparatus embraced by the invention will be more.:clearly understood when the .efollovving description is read inconnecizion withithe accompanying drawingswhich are:includedqiorillustrative purposes only, and in which:

Figure :l is :a diagrammatic side elevation of :a liquefied petroleum:gas distributing system embodying the-invention; I

Figure ;2 is :an enlarged vertical sectionai view of a preferred .iormof anti-freeze vapor introducing device included the Figure 1 system;

and

Figure F3 is a side elevation of :a portion of a natural gasdistributing system embodying the invention, another form of anti-freezevapor introducing device being shown in vertical section.

Referring particularly to Figure 1, the numeral 5 designates a pressurestorage tank in which a zpfitroleumfgasisuch as butane or propanerisfstored under its cum vapor pressure in hothiits liquid .andyaporphases. A suitable shut off valve -6 is installed in the upper endof the tank to :control or stop the fiow of vaporized gas through thepipe .l-ines and 8,, to the pressure reducer and regulator S. A-se-rvicepipe line deserves .tocarry the gas at reduced pressure from the reducer-9 to gas using appliances such as stoves, gas :enginesetc. (notshoWn-l.

The system thus .far described is-conventional,

and includes only conventional apparatus, which it is unnecessaryto'illustrate or describe in detail. When petroleum gas is stored in thetank, the pressure in the system varies with the surrounding temperatureof the air or earth, as the case may be. With propane, the pressure isrelatively highof the order of 125 to 160 p. s. i. The vaporized gas isconducted to the pressure reducer 8 at this pressure, where it passesthrough an orifice inside the reducer, and is permitted to expandrapidly, reducing the pressure of the gas to a relatively lowpressure-between about 5 p. s. i. to 2 ounces per square inch asdesired.

The rapid expansion of the gas, as it emerges from the pressure reducerorifice, has a refrigerating effect in accordance with the laws ofphysics, and produces a temperature within the regulator considerablylower than the freezing temperature of water. Under such low temperatureconditions any moisture carried by the gas is condensed to a liquid andpromptly freezes at or near the reducer inlet, often shutting off thisinlet and completely stopping gas flow through the service line 50. 7

To my knowledge there has previously been only two methods of preventingthe freezing of moisture carried by the gas. One is the exteriorapplication of heat to the reducer housing to prevent the interiortemperature from dropping below the freezing temperature of water. Theother method is the introduction of a liquid antifreeze into the tank 5.The heat method has involved many difficulties. It has required themanufacture of a water or air jacket for the reducer, the provision of ameans for heating the air or water, means for circulating air or waterthrough the jacket, temperature control means, etc.

The introduction of liquid anti-freeze into the tank has also involveddifficulties, primarily due to the high pressure under which the gasmust be stored. Since it is not advisable to pump air into the storagetank, the anti-freeze method requires portable compressor equipment, apressure hose sufficiently long that it will contain the required amountof anti-freeze liquid, valve f1- tings at each end of the hose, a meansof evacuating air from the hose, etc. One end of the hose must beattached to the tank shut oif valve 6, which usually involvesdisconnecting the pipe line i. The other end of the hose is attached toa pump and air is then evacuated from the hose. The pump intake mustthen also be attached to the storage tank 5, or to a portable storagetank containing the same type of liquid gas. Such work often requireshours of time on the part of one or two men, in addition to the truckand other equipment mentioned above.

I have found that by providing a suitable antifreeze containingreservoir H capable of withstanding the maximum operating pressure ofthe system, and by aifording open communication between the upper end ofthis reservoir and the gas service pipes, sufficient anti-freeze vaporwill be introduced into the gas flowing through the line to prevent.freezing of the moisture which condenses from the gas under lowtemperature conditions. 7

The Figure 1 reservoir H is shown more clearly in Figure 2. It is simplya hollow body 12 having 5 a threaded inlet 13, and a threaded outlet H3.Its upper end is provided with a threaded filler opening I5, whichreceives a filler plug i6.

Installation of the reservoir is accomplished quickly by one man. Thevalve 6 isshut oif and 4 the adjacent ends of the pipes 1 and 8 areconnected to the reservoir inlet 13 and outlet it, respectively.Anti-freeze liquid is then poured into the reservoir until the liquidlevel is just below the inlet-outlet level. The filler plug is thenreplaced, the valve 8 opened, and gas begins to flow through the upperportion of the antifreeze reservoir. The vapor pressure of theantifreeze liquid causes a certain amount of its vapor to mix with thegas flowing through the pipe line.

It should be pointed out that the liquid antifreeze used should have avapor pressure which is sufiiciently high at any given temperature thatits vapor will mix with the vapor of water at the same temperature insuch ratio that the resulting vapor mixture (water and anti-freeze) whencondensed to a liquid by cooling, will have a freezing point below thetemperature produced within the reducer by the rapid expansion of thevaporized gas flowing through the system. I have found that butyl,methyl, ethyl, and isopropyl alcohols and acetone and methyl ethylketone will all serve the purpose. There are undoubtedly otheranti-freeze liquids which will serve equally well. Each of the onesmentioned has a vapor pressure higher than th vapor pressure of water atthe same temperature. According to the laws of physics when any one ofthem is confined and subjected to the vapor pressure of water at thesame temperature, the resulting vapor mixture will be made up of amountsof each vapor in proportion to their respective vapor pressures. Theresulting vapor mixture will therefore contain a greater percentage ofantifreeze molecules than water molecules. The freezing point of thecondensate. of this vapor mixture (water and anti-freeze) will thereforebe very materially lower than the freezing point of water. This is thetheory behind the effective operation of my improved gas distributingsystem. However, the method embraced by this invention is not dependenton the introduction of anti-freeze vapor into the gas in any particularmanner. .The introduction of such vapor may be accomplished in otherways. Anti-freeze vapor could be introduced into the system by means ofa pump, for instance, or it could be jetted into the system under adesired pressure. It could even be introduced into the flowing gas at apoint inside the pressure reducer, which is, of course, embraced by theinvention.

Referring to Figure 3, a different type of antifreeze reservoir isshown. This reservoir H is in the form of a pressure bottle having asingle opening at its upper end. It openly communicates with thenatural'gas pipe line 18 and i9 through a nipple 2'0, the other end ofwhich is attached to a 4-way pipe joint 2|. To fill the reservoir withanti-freeze liquid it is only necessary to remove a plug 22 from thejoint. This embodiment of the means for introducing antifreeze vaporinto any gas distributing system produces results fully equal to thoseproduced by the Figure 2 embodiment.

From the above explanation it will be clearly understood that the methodembraced by my invention involves the operation of any gas distributingsystem in the usual manner, but with the additional step of introducinganti-freeze vapor into the vaporized gas either at the pressure reduceror prior to its arrival at the pressure reducer. Aside from this methodof operating a gas distributing or dispensing system, devices similar tothose disclosed for introducing the anti-freeze vapor are definitely apart of the invention, even though the devices are simple, and eventhough the method may be carried out by other means.

Having described the invention with sufficient clarity to enable thosefamiliar with the art to practice it, I claim:

1. In operating a liquified gas system which includes a tank in whichgas is stored in both its liquid and vapor phases, a pressure reducer,appliances for using the gas in vaporized form, and pipe lines forconducting the vaporized gas from the tank to the pressure reducer andfrom the reducer to the appliances, the method which comprises the stepsof passing the vaporized gas under relatively high pressure from thetank to the pressure reducer; introducing into the gas prior to itsarrival at the pressure reducer a suificient quantity of vaporizedanti-freeze to prevent the freezing, during the rapid expansion of thegas within the pressure reducer, of any moisture which may be carried bythe gas; and conducting the gas under relatively low pressure from thepressure reducer to the gas using appli- I communication with the lineconnecting the source to the reducer; a filler inlet in the upper end ofsaid reservoir; and a filler plug for said inlet.

3. In a liquified gas system, the combination with a tank in which gasis stored in both its liquid and vapor phases, a pressure reducer,appliances for using the gas in vaporized form, and pipe lines forconducting the vaporized gas from the tank to the reducer and from thereducer to the appliances, of: a closed anti freeze reservoir having aninlet and an outlet located near its upper end, and installed in thepipe line connecting the tank to the reducer; a filler inlet in theupper end of the reservoir; and a filler plug for said inlet.

JACOB A. DETHEROW.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,040,886 Claude Oct. 8, 19121,702,683 Claude Feb. 19, 1929 1,726,018 Farrar Aug. 27, 1929 1,794,185Lemoine Feb. 24, 1931 1,809,833 Davenport June 16, 1931 2,155,340 StroudApr. 18, 1939 2,305,314 Little Dec. 15, 1942

